Carburetor



July 29, 1930. c. L. RAYFIELD 1,771,852

CARBURETOR Original Filed Nov. 3, 1919 3 Sheets-Sheet 1 July 29, 1930. c. L. RAYFI LD 1,771,862

CARBURETOR Original Filed Nov. 5, 1 3 Sheets-Sheet 2 CZzaris K Fay/ idel RAYFIELD 1,771,862

CARBURETOR Original Filed Nov. 5, 1919 3 Sheets-Sheet 3 WW HlH vE 4:7 Charles J. a fz'c'la Jul 29, 1930 Patented July 29, 1930 UNITED STATES PATENT OFFICE CHARLES L. RAYFIELD, OF CHICAGO, ILLINOIS, ASSIGNOB, BY MESNE ASSIGNMENTS, TO MARVEL CARBURETEB COMPANY, OF FLINT, MICHIGAN, A CORPORATION O1 INDIANA V,

\ cnrmunnron Original application filed November 3, 1919, Serial No. 335,390. Divided and this application filed .J'uly 20, 1925. Serial No. 44,641.

This invention relates to a carburetor, and especially to regulatin' the pressure within the fuel supply cham er, this application being a division of my copending application for Carburetor, which resulted in Patent No. 1,605,280, issued November 2, 1926.

It is an object of this invention to provide means regulating the admission of air into the fuel supply chamber of a carburetor to govern the depression efi'ect therein as fluid is withdrawn therefrom. This regulation of the depression effect in the fuel supply chamber creates an important modificatlon of fluid flow from the carburetor nozzles, and thereby permits a restriction of the action thereof in step with the requirements of a proper fuel and air ratio over a wide range of speed and load conditions.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

This invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a side elevation of a horizontal outlet type of carburetor partly in section, to show one embodiment of this invention.

Figure 2 is a horizontal section on the line 11-11 of Figure '1.

Figure 3 is a fragmentary vertical section on the line IIIIII of Figure 2.

Fi ure 4 is a section on the line IV-IV of Figure 2.

Figure 5 is a fragmentary section on the line V-V of Figure 2.

As shown on the drawings:

The particular carburetor chosen for illustration comprises a horizontal passaged casing 10 containing a venturi 11, choke 12 and butterfly throttle 13. This carburetor is described in detail in my copending application mentioned hereinbefore, and is not to be constued as a limitation of the application of the invention involved in the present application. A compound low speed nozzle 14 is shown, the central tube 15 of which is fed from the float chamber 20. The particular carb retor shown maintains fuel in two levels, the fuel entering through the connection 17 to an upper fuel chamber 18 shown in Figure 2 and overflowing through a stand pipe 19 to fill the float chamber 20. The upper chamber 18 supplies fuel to the high speed nozzle 21 through passage 70.

A float 71 in the chamber 20 moves a lever 72 pivoted at 73, the bottom of a trian ular needle valve stem 74 resting on the ever. This valve stem extends through the stand pipe 19, the upper end terminating in a point 75 which 'coacts with a valve seat 76 controlling the fuel inlet passage 77.

An adjustable needle valve 78 controls the flow of fuel from the upper chamber 18 into a passage 79 opening into the recess 80 in the outerv nozzle 14. The passage 79 has a verti cal standpipe or well 81 connected thereto, an air bleed passage 82 being provided at the top of the well to permit emptying thereof to supply the acce eration demand.

An air inlet passage 22 is provided for the float chamber in an extension 23 of the casing as shown in Figure 4, and is controlled by a manuall adjustable needle valve 24 which is locke in adjusted position by the nut 25. The shaft 26 carrying the choke valve 12 is extended downwardly through a boss 27 on the cover of the float chamber and is cored axially at 28 to meet the transverse cored passage 29. When the choke valve is closed this transverse passage 29 registers with ports 30 in the boss 27 to permit free access of air to the float chamber under this condition as the valve restricted inlet passage 22 is designed to restrict the normal air the float chamber.

As clearly shown in Figures 3 and 1 the lower end of the throttle valve shaft 31 is drilled axially to afford a passage 47 and is drilled transversely with apertures 48, 49 and 50, respectively. Said passage 47 is closed above the transverse aperture 50 by plug 51 and similarly at the end of the shaft by another plug 52. Said throttle valve shaft ,31 is also rovided with a peripheral groove 53 throug which the aperture 48 communicates, and cored within the casin section 10 in register with the ooved'an transverse aperture 48 is a priming passage 54 commu supply; to

nicating with an inclined priming passage 55 leading into the outlet of the carburetor beyond the throttle valve 13 thereof. This passage 54 communicates with an enlarged passage 56 formed in the casing section 10 shown in dotted lines in Figure 1, and leads to and communicates .with avertical passage 57 formed in an extension on one side of the casing section 10 as shown in Figure 1. Also communicating into the lower end of the passage 57 is an idling tube or nozzle 40 which at its lower end connects with a passage formed in a vertical extension 59 on the float chamber and communicating into the interior of said chamber at its lower end. Rotatably mounted in the upright passage 57 is a tubular rotatable closure element 60 having an aperture 61 near its lower end adapted to register with a laterally directed air inlet passage 62 formed on the side of the casing section 10 and communicating into the passage 57 through said tubular member 60 when the same is in 0 en position as shown in Figure 1. Threaded into the tubular plug as shown and extending downwardly only sufli ciently to partially restrict the opening 61 is a stem 63 with a head 64 and the adjustment thereof determines the-quantity of fuel withdrawn by suction from the nozzle 40 and this depends upon the conditions of operation thereof. ttached upon the upper end of the tubular member is a lever 65. Said lever 65 is connected upon the upper end of the vertical shaft 11 for the butterfly choke valve 10.

The transverse aperture 49 through the "throttle valve shaft 31 hereinbefore mentioned and clearly shown in Figures 3 and 1 is adapted to register with an air port 49 shown directly in rear of said aperture in Figure 3 and provided in the casing section to admitair int the upper portion of the canal or passage within the throttle valve shaft 31 when the throttle is closed.

The passage 68 communicates downwardly and into the upperend of the float chamber 20 and when the transverse aperture 50 registers with the passage 68 the interior of the float chamber 20 is opened to the atmosphere so thatatmosphericpressure may be realized upon the fuel'therein.

' The operation is as follows:

Assume first that the carburetor contains fuel andthe motor to which the carburetor is attached is about to be started. The throttle valve 13 may be partially o ned but the choke valve is entirely closed. incident with the closing movement of the choke valve 12, the valve port ssages 28, 29 and 30 are opened to. admit air into the float chamber and rotational adjustment of the tubular valve element 60 shown in Figure 1 takes place, to close oi the air inlet passage 62 and as a result, the chamber 57 can only receive inlet thereto from the pipe 59 which communicates with the passage leading to the lower end of the float chamber 20. The outlet from the chamber 57 consists of the passage 56 whlch leads. to the passa e 54 and this registers with let end of the carburetor beyond the throttle valve 13.

The result of this is a direct passage for raw fuel from the bottom of the float chamber into the outlet of the carburetor. A small amount of air is also admitted through the intermediate port 49 in the throttle valve shaft which communicates with the canal 47 and with an air inlet port in the carburetor casing, but the relative areas of the rts for air and fuel are in favor of the fue so that a very rich mixture is supplied the carburetor for the purpose of starting the motor. Immediately after the motor is started if advisable, the choke valve 12 is fully opened and as a consequence the air inlet to the float chamber is closed and the tubular valve element 60 is rotated into the position shown in Figure 1 so as to open the air inlet 62 into the chamber 57 thus breaking the suction effect to the float chamber through the pipe 59. The extent of adjustment of the tubular valve element 60 consequently determines the draft or suction effect imposed upon the pipe connection 59 leading to the fuel in the float chamber. Adjustment of the valve '60 to open position changes the relative areas of air to fuel passa es, and enlarges the relative air areas to the uel areas.

When the choke valve 12 is fully opened the valve element 60 is also ad'usted into full open position so as to provlde a break in t e suction or draft effect in chamber 57 which causes a flow of fuel from the float chamber. The extent of opening afforded by the valve element 60, however, is determined by the adjustment of the stem 63, by its head 64, and this is the ad'ustment for idling speeds of the engine. T at is to say, the fuel withdrawn by suction through the tube40 depends upon the restriction or suction efl'ect permitted by inlet of air into :the chamber 57 according to the adjustment of the stem 63 and the valve 60.. A further restriction to the supply of fuel through the tube 40 is the regulated inlet for air into the float chamber by the needle valve 24.

After the idling adjustments have been fnade, the intermediate speed adjustments are controlled by the needle valve air inlet 24 as the throttle and choke valve stems under such conditions are both turned so as to cut off the inflowof air to the float chamber.

I am aware that many changes may be made and numerous detailsof construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting pression in said chambers by controlling the admission of air thereto.

2. A carburetor comprising a carbureting chamber, fuel supply means for supplying fuel thereinto, a fuel supply chamberfor supplying'fuel to said means, a throttle valve stem, and an air port in the throttle valve stem controlling the admission of air into the fuel supply chamber to regulate the depres sion therein as airor fuel is withdrawn therefrom.

3. In a carburetor of the class described a fuel chamber, a second fuel chamber to supply fuel thereto, a compound compensating nozzle communicating individually with both of said chambers, a throttle valve controlling the outlet of mixturefrom the carburetor, and means regulatable therewith to vary the depression in said chambers by controlling the admission of air thereinto.

In testimony whereof I have hereunto subscribed my name.

7 CHARLES L. RAYFIELD. 

